<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
  <ul id="ul">
    <li>西施</li>
    <li>貂蝉</li>
    <li>昭君</li>
    <li>凤姐</li>
    <li>芙蓉姐姐</li>
  </ul>
  <input type="button" value="按钮" id="btn" />

</body>
</html>